As a memory architecture of an information processing device, a UMA (Unified Memory Architecture) is known. The UMA is a memory architecture in which a host and a device share and use a memory mounted in the host.
When shifting to a sleep mode as a low power consumption mode, in a memory device having a non-volatile memory, power supply to almost all circuits in the memory device is stopped. On the other hand, when returning from the sleep mode to the normal mode, it is expected to shorten the returning time as possible after power supply returns in the memory device.